Air flow measuring device

ABSTRACT

A sensor assembly includes a sensor portion and a sensor circuit, which are integrated with each other and configured to measure an air flow quantity. A thermistor is configured to measure an air temperature. A metal plate includes a grounding end terminal. One lead wire of the thermistor is joined electrically with the grounding end terminal. The sensor circuit is disposed on the metal plate. The sensor circuit is entirely overlapped with the plate shape portion in a direction perpendicular to the metal plate.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 15/178,628, filed Jun. 10, 2016, which is based onreference Japanese Patent Application No. 2013-99164 filed on May 9,2013 and claims the benefit of U.S. application Ser. No. 14/262,998,filed on Apr. 28, 2014, the disclosure of which is incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to an air flow measuring deviceconfigured to measure a quantity of air flow.

BACKGROUND

For example, Patent Document 1 discloses a conventional air flowmeasuring device, which includes a sensor assembly and an end terminalmolded in a resin housing.

Patent Document

Publication of unexamined Japanese patent application No. 2011-106868

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a schematic sectional view showing a main portion of an airflow measuring device; and

FIG. 2 is a schematic sectional view showing the air flow measuringdevice equipped to a duct.

DETAILED DESCRIPTION First Embodiment

A first embodiment of the present disclosure will be described withreference to FIGS. 1 and 2. An air flow measuring device 1 is equippedto an air intake duct 2, which is to draw intake air to an internalcombustion engine of a vehicle when the vehicle is, for example,travelling. More specifically, the air intake duct 2 is equipped to, forexample, a duct, which is located at an outlet of an air cleaner, orequipped to an intake pipe at a downstream of an air cleaner.

The air flow measuring device 1 is a thermal airflow meter configured tomeasure a quantity of intake air (intake air quantity, air flowquantity) drawn into the engine.

The air flow measuring device 1 includes a resin housing 3, a sensorassembly 6, and end terminals 8. The resin housing 3 (passage formationmember) is equipped to the air intake duct 2. The sensor assembly 6includes a sensor portion 4 and a sensor circuit 5, which are integratedwith each other. The sensor portion 4 is configured to measure the airflow quantity. A thermistor 7 is equipped independently (separately)from in the sensor assembly 6. The thermistor 7 is configured to measurea temperature of intake air (air temperature). The end terminals 8 areconfigured to electrically connect the sensor assembly 6 with thethermistor 7.

The resin housing 3 is a secondary-molded product of resin. The interiorof the resin housing 3 forms a bypass passage α and a sub-bypass passageβ. The bypass passage α is configured to draw a part of intake air,which flows through the air intake duct 2. Specifically, the air intakeduct 2, which is equipped with the air flow measuring device 1, has anAFM mount hole. The AFM mount hole extends through the air intake duct2. The AFM mount hole may communicate the inside of the air intake duct2 with the outside of the air intake duct 2. A main portion of the resinhousing 3 is inserted from the outside of the AFM mounting hole into theair intake duct 2. Mores specifically, a portion of the resin housing 3,which forms the bypass passages α and β, is inserted into the air intakeduct 2. Subsequently, the resin housing 3 is fixed to the air intakeduct 2 by, for example, fastening the resin housing 3 to the air intakeduct 2 with a tapping screw. In this way, the air intake duct 2 isequipped to the air flow measuring device 1.

The sensor portion 4 is inserted into the sub-bypass passage β. Thesensor portion 4 is configured to generate, for example, a voltagesignal according to the a quantity of intake air flow, which is a partof intake air flow passing through the sub-bypass passage β. In thepresent example, the sensor portion 4 employs a chip-form configuration.More specifically, the sensor portion 4 is configured with, for example,a thin film-type circuit board. The sensor circuit 5 is configured tocompensate the quantity of intake air flow detected with the sensorportion 4. The sensor circuit 5 is further configured to A/D convert thecompensated quantity of intake air flow and to send a signalrepresenting the quantity of intake air flow. The sensor circuit 5 mayimplement, for example, frequency modulation on the compensated quantityof intake air flow.

The sensor assembly 6 is formed by integrally molding the sensor portion4 and the sensor circuit 5 of primary molding resin. More specifically,the sensor portion 4 has a section, which includes a sensor circuitboard and excludes an air flow quantity measurement element, and thesection of the sensor portion 4 is integrally molded with the sensorcircuit 5. Subsequently, the sensor portion 4 and the sensor circuit 5,which are integrally molded together, are further molded with the resinhousing 3. The sensor circuit 5 is molded with the sensor assembly 6 andis further connected electrically with an ECU (engine control unit)through a connector 9. The connector 9 is equipped to the resin housing3 and located at an upper portion of the resin housing 3 in the drawing.The ECU is located in the vehicle at a position different from aposition at which the air flow measuring device 1 is located.

The connector 9 includes a resin coupler 10 and the end terminals 8. Theresin coupler 10 is formed as a part of the resin housing 3. The endterminals 8 are exposed at those ends inside the resin coupler 10. Asshown in FIGS. 1 and 2, the connector 9 is a male connector includingthe resin coupler 10 and the end terminals 8. The resin coupler 10 isformed in a female shape. The end terminals 8 are projected from abottom surface of the resin coupler 10 into the resin coupler 10. In thepresent embodiment, the end terminals 8 includes an electric powersource end terminal 8 a, a grounding end terminal 8 b, a flow output endterminal 8 c, a control end terminal 8 d, a temperature output endterminal 8 e, and/or the like.

The connector 9 described above is one example and may be modifiedarbitrarily. For example, the connector 9 may be a female connector,dissimilarly to the present embodiment. In addition, according to thepresent embodiment, the connector 9 is configured to receive a connecteddevice at its upper portion from its upper side. It is noted that, theconnector 9 may receive a connected device at its side portion in alateral direction. The arrangement of the end terminals 8 is one exampleand may be modified arbitrarily.

The sensor assembly 6 includes external connection terminals 11. Theexternal connection terminals 11 are configured to be connectedelectrically with the sensor portion 4 and/or the sensor circuit 5. Theexternal connection terminals 11 are configured to connect the sensorportion 4 and the sensor circuit 5 electrically with an external device.The external device is outside a molded product, which is molded of theprimary molding resin to form the sensor assembly 6. That is, theexternal connection terminals 11 are common to the end terminals 8. Inother words, the external connection terminals 11 are formed of commoncomponents with the end terminals 8.

Specifically, the external connection terminals 11 according to thepresent embodiment are formed by implementing a press working to punchthe external connection terminals 11 out of a metal plate, which isexcellent in conductivity. The metal plate is, for example, a copperthin plate. The external connection terminals 11 are formed in this way,thereby to simultaneously from the electric power source end terminal 8a, the grounding end terminal 8 b, the flow output end terminal 8 c, thecontrol end terminal 8 d, and the temperature output end terminal 8 e.The grounding end terminal 8 b also serves as a grounding electrode ofthe sensor portion 4, the sensor circuit 5, and the thermistor 7. Thesensor portion 4 and the sensor circuit 5 are equipped to the groundingend terminal 8 b in the sensor assembly 6. The sensor portion 4 and thesensor circuit 5 are connected by way of an electric connection element,such as a bonding wire, with corresponding end terminals, such as theelectric power source end terminal 8 a, the grounding end terminal 8 b,the flow output end terminal 8 c, the control end terminal 8 d, and/orthe like.

To the contrary, the thermistor 7 is located outside the resin housing 3and exposed to the exterior of the resin housing 3. Specifically, thethermistor 7 is a resistive element, which changes its resistanceaccording to change in temperature. One lead wire of the thermistor 7 isjoined electrically and mechanically with an end of the grounding endterminal 8 b. The end of the grounding end terminal 8 b is exposed tothe interior of the air intake duct 2. The other lead wire of thethermistor 7 is joined electrically and mechanically with an end of thetemperature output end terminal 8 e. The end of the temperature outputend terminal 8 e is exposed to the interior of the air intake duct 2.

It is noted that, the portions of the end terminals 8, which are joinedwith the thermistor 7, may be restricted from being exposed directly toair, dissimilarly to the present embodiment. That is, the end of thegrounding end terminal 8 b and the end of the temperature output endterminal 8 e, which are joined with the thermistor 7, may be restrictedfrom being exposed directly to air. That is, the thermistor 7 may befirst joined with the grounding end terminal 8 b and the temperatureoutput end terminal 8 e of the end terminals 8, and subsequently, thejoined portions between the thermistor 7 and the end terminals 8 may bemolded with the resin housing 3.

(Effect)

As described above, in the air flow measuring device 1 according to thepresent the embodiment, the external connection terminals 11 of thesensor assembly 6 also functions as the end terminals 8 of the sensorassembly 6 and the thermistor 7. Thus, the present configuration enablesto reduce the number of components in this way, compared with aconventional configuration. In addition, the present configurationenables to omit an assembling and joining process, which is formechanically and electrically assembling and joining the externalconnection terminals 11 with the end terminals 8, from entiremanufacturing process for the air flow measuring device 1. Thus, thepresent configuration enables to reduce a manufacturing cost for the airflow measuring device 1.

In addition, the present configuration enables to integrate(commonalize) the external connection terminals 11 with the endterminals 8. Therefore, the present configuration enables to reduce acost incurred for joining the external connection terminals 11 with theend terminals 8. Thus, the present reduction in manufacturing costenables to reduce entire cost for the air flow measuring device 1. Inaddition, the present configuration enables to reduce margins via whichthe external connection terminals 11 are joined with the end terminals8. Therefore, the present configuration enables to downsize the air flowmeasuring device 1.

INDUSTRIAL APPLICABILITY

According to the above embodiment, the configuration of the presentdisclosure is applied to the air flow measuring device 1 configured tomeasure a quantity of intake air drawn into the engine. It is notedthat, the configuration of the present disclosure may be applied to anair flow measuring device, which is for a device other than an engine.

As described above, the air flow measuring device according to thepresent disclosure includes the sensor assembly having the externalconnection terminal(s). The external connection terminal(s) alsofunctions as the end terminal(s) of the sensor assembly and/or thethermistor. Therefore, the present configuration enables to reduce thenumber of components. In addition, the present configuration enables toomit the assembling and joining process, which is for joining theexternal connection terminal(s) mechanically and electrically with theend terminal(s). Furthermore, the present configuration enables toreduce the margins via which the external connection terminal(s) isjoined with the end terminal(s). Therefore, the present configurationenables to reduce the manufacturing cost and the size of the air flowmeasuring device.

It should be appreciated that while the processes of the embodiments ofthe present disclosure have been described herein as including aspecific sequence of steps, further alternative embodiments includingvarious other sequences of these steps and/or additional steps notdisclosed herein are intended to be within the steps of the presentdisclosure.

While the present disclosure has been described with reference topreferred embodiments thereof, it is to be understood that thedisclosure is not limited to the preferred embodiments andconstructions. The present disclosure is intended to cover variousmodification and equivalent arrangements. In addition, while the variouscombinations and configurations, which are preferred, other combinationsand configurations, including more, less or only a single element, arealso within the spirit and scope of the present disclosure.

What is claimed is:
 1. An air flow measuring device comprising: a sensorassembly including a sensor portion and a sensor circuit, which areintegrated with each other and configured to measure an air flowquantity; a thermistor configured to measure an air temperature; and ametal plate including a grounding end terminal, wherein one lead wire ofthe thermistor is joined electrically with the grounding end terminal inthe sensor assembly, the sensor circuit is disposed on the metal plate,and the sensor circuit is entirely overlapped with the metal plate in adirection perpendicular to the metal plate.
 2. The air flow measuringdevice according to claim 1, wherein the sensor circuit entirelycoincides with at least a part of the metal plate in the direction. 3.The air flow measuring device according to claim 1, wherein the metalplate further includes a metal body portion integrated with thegrounding end terminal, the sensor circuit is disposed on the metal bodyportion, and the sensor circuit entirely coincides with at least a partof the metal body portion in the direction.
 4. The air flow measuringdevice according to claim 1, further comprising: a connector; and atleast four end terminals extending to the connector.
 5. The air flowmeasuring device according to claim 1, further comprising: a control endterminal; and at least one end terminal, wherein the control endterminal, the at least one end terminal, and the grounding end terminalextend in a same direction, and the control end terminal is located atan outermost position among the control end terminal, the at least oneend terminal, and the grounding end terminal.
 6. The air flow measuringdevice according to claim 1, further comprising: a connector; anelectric power source end terminal; a flow output end terminal; acontrol end terminal; and a temperature output end terminal, wherein theelectric power source end terminal, the grounding end terminal, the flowoutput end terminal, and the temperature output end terminal extend tothe connector and are longer than the control end terminal.
 7. The airflow measuring device according to claim 1, further comprising: atemperature output end terminal, wherein the grounding end terminal andthe temperature output end terminal are adjacent to each other.
 8. Theair flow measuring device according to claim 1, further comprising: anelectric power source end terminal; and a temperature output endterminal, wherein the grounding end terminal is located between theelectric power source end terminal and the temperature output endterminal.
 9. The air flow measuring device according to claim 1, furthercomprising: a flow output end terminal; and a temperature output endterminal, wherein the grounding end terminal is located between the flowoutput end terminal and the temperature output end terminal.
 10. The airflow measuring device according to claim 1, further comprising: anelectric power source end terminal; and a flow output end terminal,wherein the electric power source end terminal and the flow output endterminal are adjacent to each other.
 11. The air flow measuring deviceaccording to claim 1, further comprising: an electric power source endterminal; a flow output end terminal; and a control end terminal,wherein the flow output end terminal is located between the control endterminal and the electric power source end terminal.
 12. The air flowmeasuring device according to claim 1, further comprising: a connector;an electric power source end terminal; a flow output end terminal; and atemperature output end terminal, wherein the electric power source endterminal, the grounding end terminal, the flow output end terminal, andthe temperature output end terminal are longer than a half of a lengthof the connector.
 13. The air flow measuring device according to claim1, further comprising: a connector; and a control end terminal, whereinthe control end terminal is shorter than a half of a length of theconnector.
 14. The air flow measuring device according to claim 1,further comprising: an electric power source end terminal; a flow outputend terminal; a control end terminal; and a temperature output endterminal, wherein each of the electric power source end terminal, thegrounding end terminal, the flow output end terminal, the control endterminal, and the temperature output end terminal is bent at least oneintermediate portion.
 15. The air flow measuring device according toclaim 14, further comprising: a connector, wherein the at least oneintermediate portion includes a first intermediate portion and a secondintermediate portion, and the first intermediate portion is on a side ofthe sensor assembly, the second intermediate portion a side of theconnector, each of the electric power source end terminal, the groundingend terminal, the flow output end terminal, the control end terminal,and the temperature output end terminal is bent at the firstintermediate portion to extend outward in a width direction of theconnector, and each of the electric power source end terminal, thegrounding end terminal, the flow output end terminal, the control endterminal, and the temperature output end terminal is bent at the secondintermediate portion to extend straight in a height direction of theconnector.
 16. The air flow measuring device according to claim 1,wherein the metal plate is a punched copper thin plate formed by pressworking.
 17. The air flow measuring device according to claim 1, whereinthe thermistor is joined with the metal plate at a joined portion, andthe joined portion is molded with resin.
 18. An air flow measuringdevice comprising: a sensor assembly including a sensor portion and asensor circuit, which are integrated with each other and configured tomeasure an air flow quantity; a thermistor configured to measure an airtemperature; and a metal plate including a grounding end terminal,wherein one lead wire of the thermistor is joined electrically with thegrounding end terminal, the sensor circuit is disposed on the metalplate, and the sensor circuit entirely coincides with at least a part ofthe metal plate in a direction perpendicular to the metal plate.
 19. Theair flow measuring device according to claim 18, wherein the metal platefurther includes a metal body portion integrated with the grounding endterminal, the sensor circuit is disposed on the metal body portion, andthe sensor circuit entirely coincides with at least a part of the metalplate in the direction.
 20. An air flow measuring device comprising: asensor assembly including a sensor portion and a sensor circuit, whichare integrated with each other and configured to measure an air flowquantity; a thermistor configured to measure an air temperature; and ametal plate including a grounding end terminal, wherein one lead wire ofthe thermistor is joined electrically with the grounding end terminal,the sensor circuit is disposed on the metal plate, the sensor circuithas a first projected area projected in a direction perpendicular to themetal plate, the metal plate has a second projected area projected inthe direction, and the first projected area is entirely encompassedwithin the second projected area.